Phase detection of an electrical signal may be used to measure the real and imaginary components of the impedance of an electrical device under test. For convenience, it is desirable that the time necessary to perform the phase detection be kept short and for accuracy it is desirable that detection errors be kept to a minimum.
Phase detection, as performed in the prior art, has been accomplished with the use of a switched single detector as is described in Laid Open Japanese Patent No. 30375/1978. While high degrees of measurement accuracy may be achieved with the use of such a switched single detector, the phase detection method tends to be very time-consuming.
In accordance with the illustrated preferred embodiment of the present invention, a phase detection method permits rapid phase detection to be accomplished with a high degree of measurement accuracy. A dual detector apparatus is utilized to make phase measurements of two unknown signals relative to a reference signal. Repeated measurements of the two unknown signals are made and an incremental phase shift is injected between successive measurements. The individual measurements are averaged to yield a highly accurate phase measurement.